Composition for reclaiming pulp from waste papers

ABSTRACT

The reclamation of purified and reusable pulps from various types of waste papers by first shredding the paper into fine pieces, boiling the shredded paper in a chemical solution containing an alkali metal hydroxide, an alkali metal carbonate an alkali metal bicarbonate and sodium borate, water washing the chemicals from the cooked paper and then bleaching the pulp with a chemical bleach at elevated temperature.

United States Patent 1 Gleason et al.

COMPOSITION FOR RECLAIMING PULP FROM WASTE PAPERS Inventors: C. RoyGleason, Chicago; Gordon A. Thomas, Wilmette, both of 111.

World-Wide Paper Reclamation,

Assignee:

' Inc., Chicago, 111.

Notice: The portion of the term of this patent subsequent to Oct. 16,1990, has been disclaimed.

Filed: May 25, 1973 Appl. No.: 364,110

Related U.S. Application Data Division of Ser. No. 172,600, Aug. 17,1971, Pat. No. 3,766,001.

U.S. Cl 162/8, 252/135, 252/156 Int. Cl. D2lc 5/02 Field of Search162/4, 8; 423/280, 282;

1*Feb. 11, 1975 [56] References Cited UNITED STATES PATENTS 3,218,12011/1965 Amodeo 423/282 3,671,188 6/1972 Mathis 423/282 3,766,001 10/1973Gleason et a1. 162/8 Primary Examiner--Sr Leon Bashore AssistantExaminer-William F. Smith [57] ABSTRACT 6 Claims, No DrawingsCOMPOSITION FOR RECLAIMING PULP FROM WASTE PAPERS This is a, division ofapplication Ser. No. 172,600, filed Aug. 17, 1971, now U.S. Pat. No.3,766,001.

This invention relates to the reclamation of purified and reusable pulpfrom paper which may be in the form of clay coated paper, printed paper,or paperboard, envelopes, magazines and trade papers and bond and ledgerpapers, printed, embossed or lined with various types of coloredprinting inks, magazine cover sheets, book paper, binders and the like.

Difficulty has been experienced in removing certain resinous or hot melttypes of adhesives, color of papers, such as golden rods, canaries inbonds and ledgers, and various types of inks used in the printing, bookpublishing, magazine publication and the like, and some papers embodyinglarge quantities of valuable fibers of even rag or cotton content.Rotogravure, offset, high gloss inks along with letter press inks ofinnumerable resin contents and colors that have to be removed, presentadditional problems. Many such paper wastes are being burned bythousands of tons a day and this despite inevitable paper shortagesfacing the industry.

It is most desirable to be able to reclaim the fibrous content of suchwaste papers for reuse in the making or upgrading of quality paper andpaperboard stocks for cartons and packaging. For such purposes, and asan object of this invention it is desirable to provide a simple,economical and efficient process for the removal of sizings, or binder,or various resins and other color material present in the printing inks,coating resins, binder adhesives and the like, with a view towardsyielding a clean white or colorless pulp which can be used to producequality pulp in the manufacture and upgrading of news paper, printingpaper, paperboard, envelopes, bags and other paper or cellulosicproducts.

The invention will hereinafter be described with special reference tothe reclamation of waste papers as derived from clay coated cover sheetsand magazines, trade papers, etc. which have been printed with a widevariety of differently colored printing inks and sheets taken from thecovers or bodies of magazines printed with various black and coloredprinting inks. Such printing inks are characterized by a high resinouscontent and pigments formed of carbon black, dyestuffs and the like. Itwill be understood that the hereinafter described process forreclamation of such printed magazine papers can be even more readilyadapted to the reclamation of other types of papers printed or coloredwith various types of printing inks or unprinted or uncolored paper orpaperboard.

EXAMPLE I A definite weight of printed magazines, etc. to be recovered,from cover to cover with no pages removed or without removal of any ofits inserts, is chopped or shredded while the waste paper is preferablydry. If certain large equipment is available, the magazines can be runin their entirety without cutting or without shredding.

The cut up paper is weighed, as to volume to be processed, and thenintroduced into tanks for boiling with water, preferably in the ratio of2 gallons of water per one pound of paper, with chemicals added to thewater, as hereinafter described. Boiling with agitation is car ried outfor at least minutes per batch.

Cooking composition with water: For 1 pound of chemicals [00 gramssodium hydroxide (caustic soda) dry weight 250 grams sodium carbonate(soda ash) 48 grams sodium or ammonium bicarbonate 56 grams sodiumborate (Borax) One pound of the chemical mixture is used per 10-20pounds of paper. This corresponds to -200 pounds of chemicals per ton ofpaper with the chemicals dissolved in water in the described ratio of 2gallons of the aqueous solution per pound of paper. The chemicals arebelieved to react synergistically in solution to form sodiumborocarbonate as a reactive compound.

"is desirable to cook at boiling temperature for at least 10 minuteswith vigorous agitation during the entire time but short of reduction ofthe material to a pastry pulp. Lower temperatures down to F. can be usedbut this markedly increases the reaction time in the chemical solutionso that, for practical purposes, it is desirable to make use oftemperatures above 200 F. to the boiling point temperature of 2l2 F. forthe solution. This produces a pulp that requires the addition of waterto enable the mixture to be pumped or drained from the cooking vessel.The pulp is drained and then washed with cold water.

In the process of this invention use can be made of tanks or equipmentformed of steel and, for batch operation, it is desirable to operatewith batches of 2,000 to 4,000 pounds of paper.

The boiled paper is pulped with cold water in a conventionall-lydropulper, Holland or Jordan mill, or a heater until it reaches apulp stage and is again cold water washed and screened.

The washed pulp is drained and then taken up with hot water at atemperature within the range of l l0-l40 F. and a conventional chlorinetype bleach, such as sodium hypochlorite, 5.25 active ingredient and94.75 inert, is added in the amount up to 95 gallons per ton by weightof original paper. After bleaching for from 5-20 and preferably 10-15minutes, the pulp is again washed in cold water for removal of thechlorine bleach solution. Thereafter the pulp is ready to form into wetlaps or briquetted for use in equipment for the manufacture of paper orpaperboard stock, etc. The wet laps can be shipped to near by papermills without the necessity for drying or excessive rehydrolyzationthereby to save time while avoiding over-beating or deterioration of thepulp fibers or shortening of the pulp fibers. The briquettes can bequickly rebeaten for pulp formation.

Recovery of the fibrous component of the original waste papers varies intheir yields as to the kind and classification of the waste used. Thefiber that is recovered is free of inks, clay coatings, adhesives,fillers and sizing of the type originally present in the waste paperstock and is thoroughly antiseptic and free of slimicides andfungicides. Also, germs and bacteria are killed in the chemical'boilingand treatment so that the end product is relatively pure and safe forfurther reuse. The pulp fibers can be used alone or in combination withother pulps or with rag or cotton containing pulp for use in themanufacture of fine white papers or bonds or ledgers. Kraft paper can bereclaimed from bags, envelopes, printing papers, paperboard, cartonstock or the like in high yields. According to the class of paperrecovered, the pulp can be used in controlled mixtures and percentagesthat can be standardized to meet uniform specification. Recovery ofbonds and ledgers and bleached Kraft are most desirous and give highyields of 80 percent and some 90 percent yield and offer greater demandand profit.

EXAMPLE 2 Cancelled and used bank checks and stock certificates, usuallyprinted on yellow, green or blue safety paper in any proportion can besubstituted for other high grade papers and processed, as in Example l.The reclaimed pulp is pure white with better than 80 percent recovery.

EXAMPLE 3 25-50 percent rag or cotton content paper in the form of bondpaper with engraved letterheads was processed in accordance withExample 1. Pads formed by filtering the reclaimed fiber showed highestrecovery yields of the rag and cellulose fiber without noticeabledeterioration in the fiber. White bond waste carries a premium and thuslimits the available supply, but using all colored, or all mixed,greatly increases the tonnage available for reclamation in accordancewith Example I. These papers offer no problems when processed as inExample 1.

EXAMPLE 4 Large heavy envelopes of Kraft paper, with variously coloredtags pasted on the surface and with cancelled postage stamps left onwere processed in various amounts. Some were unbleached and left asnatural Kraft and some were bleached to different stages on up to realwhite. The paper was treated as in Example I, but with the originalvigorous boiling cook lasting for to minutes and use was made ofslightly longer bleaching.

A Kraft pulp was reclaimed having a slight yellowish tinge with arecovery yield of more than 80 percent of the fiber originally presentin the envelopes. When processed a little longer in bleach, the yieldwas the same but the pulp was very white.

The process, as described in Examples l-4, is subject to a number ofvariations.

In the chemical bath, in which the disintegrated paper is cooked, thesodium hydroxide can be substituted in whole or in part in Example 1 byother alkali metal hydroxides, such as potassium hydroxide. The sodiumcarbonate can be substituted in whole or in part with other alkali metalor ammonium carbonates in equivalent amounts, and the sodium or ammoniumbicarbonate can be substituted in whole or in part with other alkalimetal bicarbonates.

While it is preferred to make use of the chemical components of thesolution in the ratio described in Example variation of chemicals in theamount of 100-200 i parts by weight of alkali metal hydroxide, 150-250 120 percent parts by weight of alkali metal carbonate, 48 :L 20 percentparts by weight of the bicarbonate and 56 i 20 parts by weight of theborate can be employed. The amount of chemical solids per pound of papercan vary within the range of one part by weight of chemical solids pe'rl0-30 parts by weight of paper, the best results being secured in theratio employed in Example 1 of one part by weight chemical solids perl0-20 parts by weight of paper. The solution can be formulated tocontain the described amounts of chemicals in solution in the ratio of20 gallons per 0.5 to 2 pounds of chemicals and preferably in the ratioof 20 gallons solution per 0.8 to 1.2 pounds by weight of chemicals.

The paper can be boiled in the chemical solution at pressures aboveatmospheric pressure with corresponding higher temperatures but it isundesirable to make use of such higher temperatures as might causedeterioration of the fibers. It is preferred to process the paper atatmospheric pressure at a temperature of about boiling pointtemperature, for the solution for about 10 to 15 minutes and for longerperiods of time at lower temperature but itis not desirable to make useof a cooking temperature of less than about 180 F. and preferably notless than 200 F.

Similarly, the chlorine bleach can be carried out at temperatures up to140 F. to below the 1 10 F. of Example l but it is undesirable to makeuse of a temperature for bleaching much below F., otherwise the desiredbleach will take an excessively long period of time, or in additionalstages, with the danger of subjecting the pulp fibers to deteriorationand increased costs.

It will be apparent from the foregoing that we have provided a new andefficient process for the reclamation of waste papers whereby a highquality pulp fiber is secured which may be used in the conventionalmanner for the production of paper and paper products.

It will be understood that changes may be made in the formulation andconditions of operation without departing from the spirit of theinvention, especially as defined in the following claims.

We claim:

1. The composition for the recovery of pulp from waste papers by aprocess which includes the step of cooking the waste paper in an aqueoussolution in which the composition is present in the dissolved state andin which the solids of the composition consist essentially of a. analkali metal hydroxide b. an alkali metal carbonate c. an alkali metal'or ammonium bicarbonate d. an alkali metal borate and present in theratio of 100-200 i 20 percent parts by weight of alkali metal hydroxide,ISO-250 i 20 percent parts by weight alkali metal carbonate, 48 i 20percent parts by weight of the bicarbonate and 56 i 20 percent parts byweight of the borate.

2. The composition as claimed in claim 1 in which the chemicals arepresent in the ratio of:

100 parts by weight of the hydroxide 250 parts by weight of thecarbonate 48 parts by weight of the bicarbonate 56 parts by weight ofthe borate.

3. The composition as claimed in claim 1 in which the alkali metalhydroxide is sodium hydroxide and in which the bicarbonate is sodiumbicarbonate.

4. The composition as claimed in claim 1 in which the alkali metalcarbonate is sodium carbonate and in which the alkali metal borate issodium borate.

5. The composition as claimed in claim 1 in which the chemicals arepresent in solution in aqueous medium in the concentration of 0.5 to 2pounds of the chemicals per 20 gallons of solution.

.6. The composition as claimed in claim 1 in which the chemicals arepresent in solution in aqueous medium in the concentration of 0.8 to 1.2pounds per 20 gallons of solution.

1. THE COMPSITION FOR THE RECOVERY OF PULP FROM WASTE PAPERS BY APROCESS WHICH INCLUDES THE STEP OF COOKING THE WASTE PAPER IN AN AQUEOUSSOLUTION IN WHICH THE COMPOSITION IS PRESENT IN THE DISSOLVED STATE ANDIN WHICH THE SOLIDS OF THE COMPOSITION CONSIST ESSENTIALLY OF A. ANALKALI METAL HYDROXIDE B. AN ALKALI METAL CARBONATE C. AN ALKALI METALOR AMMONIUM BICARBONATE D. AN ALKALI METAL BORATE AND PRESENT IN THERATIO OF 100-200 20 PERCENT PARTS BY WEIGHT OF ALKALI METAL HYDROXIDE,150-250 20 PERCENT PARTS BY WEIGHT ALKALI METAL CARBONATE, 48 20 PERCENTPARTS BY WEIGHT OF THE BICARBONATE AND 56 20 PERCENT PARTS BY WEIGHT OFTHE BORATE.
 2. The composition as claimed in claim 1 in which thechemicals are present in the ratio of: 100 parts by weight of thehydroxide 250 parts by weight of the carbonate 48 parts by weight of thebicarbonate 56 parts by weight of the borate.
 3. The composition asclaimed in claim 1 in which the alkali metal hydroxide is sodiumhydroxide and in which the bicarbonate is sodium bicarbonate.
 4. Thecomposition as claimed in claim 1 in which the alkali metal carbonate issodium carbonate and in which the alkali metal borate is sodium borate.5. The composition as claimed in claim 1 in which the chemicals arepresent in solution in aqueous medium in the concentration of 0.5 to 2pounds of the chemicals per 20 gallons of solution.
 6. The compositionas claimed in claim 1 in which the chemicals are present in solution inaqueous medium in the concentration of 0.8 to 1.2 pounds per 20 gallonsof solution.